X-ray diffraction (XRD)

What it tells you: the crystal structure of your sample

X-ray diffraction allows you to identify crystal phases in your sample, and potentially crystallographic parameters, strain and orientation information. In this technique we collect an XRD pattern at each pixel, and we can extract where a specific reflection comes from in your sample (similar to selected area electron diffraction). We can process your data to give a 1D spectra per pixel or a 2D map per pixel with corresponding XRF images.

Things to consider:

The size of your crystallites – Smaller than 50 nm, you won’t be able to see individual crystallites, bigger than 50 nm you will likely only see one or two spots in your pattern.

Q range – Our max q range is ~3.8 A but at this higher range, you won’t see a full circle (thus your spot could be elsewhere) as shown in the figure:

Signal – Signal can be low as we collect XRD patterns generally at 18 keV, where our flux is lower. You may need to count for longer to achieve a useable pattern/sufficient signal to noise ratio. If you intend to collect XRF at the same time, you will need to take into account that your XRF signal may be lower if your element of interest has an absorption edge much lower than 18 keV.

Other diffracting materials – Some substrates can have their own diffraction patterns that may get in the way of your pattern

Thickness of your sample – Our detector is in transmission, so too thick a sample would absorb any diffraction signal.